Extracellular vesicles in the pathogenesis and treatment of acute lung injury

Acute lung injury(ALI)and acute respiratory distress syndrome(ARDS)are common life-threatening lung diseases associated with acute and severe inflammation.Both have high mortality rates,and despite decades of research on clinical ALI/ARDS,there are no effective therapeutic strategies.Disruption of alveolar-capillary barrier integrity or activation of inflammatory responses leads to lung inflammation and injury.Recently,studies on the role of extracellular vesicles(EVs)in regulating normal and pathophysiologic cell activities,including inflammation and injury responses,have attracted attention.Injured and dysfunctional cells often secrete EVs into serum or bronchoalveolar lavage fluid with altered cargoes,which can be used to diagnose and predict the development of ALI/ARDS.EVs secreted by mesenchymal stem cells can also attenuate inflammatory reactions associated with cell dysfunction and injury to preserve or restore cell function,and thereby promote cell proliferation and tissue regeneration.This review focuses on the roles of EVs in the pathogenesis of pulmonary inflammation,particularly ALI/ARDS.

Clinical applications of exosome membrane proteins

Extracellular vesicles(EVs)are small membranous particles that can mediate cell-to-cell communication and which are divided into at least three categories according to their subcellular origin and size:exosomes,microvesicles,and apoptotic bodies.Exosomes are the smallest(30–150 nm)of these EVs,and play an important role in EV-mediated cell-to-cell interactions,by transferring proteins,nucleic acids and,lipids from their parental cells to adjacent or distant cells to alter their phenotypes.Most exosome studies in the past two decades have focused on their nucleic acid composition and their transfer ofmRNAs and microRNAs to neighboring cells.However,exosomes also carry specific membrane proteins that can identify the physiological and pathological states of their parental cells or indicate their preferential target cells or tissues.Exosome membrane protein expression can also be directly employed or modified to allow exosomes to serve as drug delivery systems and therapeutic platforms,including in targeted therapy approaches.This review will briefly summarize information on exosome membrane proteins components and their role in exosome–cell interactions,including proteins associated with specific cell-interactions and diseases,and the potential for using exosome membrane proteins in therapeutic targeting approaches.